In the first millionths of a second of the universe's life, protons and neutrons—the particles that make up matter—didn't exist. Instead, there was simply a hot, dense soup of even smaller particles known as quarks and gluons.

Scientists working on Brookhaven National Laboratory's STAR experiment have been studying this soup, known as quark-gluon plasma, for over a decade. Now, contributions from Fermilab's Silicon Detector Facility, or SiDet, are helping to further unveil the mystery of the moments after the big bang.

The team at SiDet has been constructing silicon detectors for about 28 years. The detectors are particularly adept at examining particle events close to the interaction point. When two particles collide, new particles are sent scattering in all directions. The point at which they split is known as the primary vertex. Sometimes, the new particles divide further, creating what are called secondary vertices.

"Usually if you want to measure things that happen very close to the region of the vertices you use silicon detectors," said Gaston Gutierrez, a scientist at SiDet.

This is what the team at the STAR experiment aims to do. They want to study the quark-gluon plasma by looking at heavy flavor particles generated in the heavy-ion collisions, but up until now have not had the resolution to do so.

The STAR collaboration intended to build new silicon detectors to increase the resolution, but risked falling behind schedule—it needed more manpower. So physicist Zhenyu Ye, an assistant professor at the University of Illinois at Chicago who joined STAR in 2012, called upon Gutierrez, one of his supervisors when he was a postdoc at Fermilab, to see if SiDet could provide help for this project. The lab agreed.

At SiDet, a team of five Fermilab technicians—Bert Gonzalez, Tammy Hawke, Michelle Jonas, Gordie Gillespie and Michael Roman—built and measured 18 detectors—known as staves—for STAR. Each stave is a long, rectangular carbon fiber core with six silicon sensors and 36 readout chips. Beams are fired through the sensors, and readout chips at one end of the detector pick up and analyze the signals released.

The work is incredibly precise. Gonzalez, for example, mounts the readout chips and silicon sensors onto the core by hand, using a microscope to make sure everything is aligned properly.

"It's always, 'Wait until you receive the parts, then hurry up and get it done,'" Gonzalez said. "But of course haste makes waste. It's best to do it right the first time."

Now that the 18 staves are completed, they will be installed onto a supporting structure, which will be integrated into the STAR experiment sometime in September.

"Help from Fermilab is really great for the project, because otherwise it may not have been finished on time," Ye said. "These people are some of the most experienced at assembling silicon detectors in the world. We are just fortunate to have them help us."

—Laura Dattaro

Photo of the Day

Shape of CDF

You might think this is a David Hockney, but it's actually an Elliott McCrory. This photo shows a seldom-seen perspective of the CDF building. Photo: Elliott McCrory, AD

In Brief

Fermilab posts latest Physics Advisory Committee report

The Fermilab Physics Advisory Committee met from June 4 to 8 to review proposals and other aspects of the Fermilab science program.

The meeting's main emphasis was on one proposal, one Letter of Intent and one Expression of Interest submitted to the laboratory before the meeting:

Based on the PAC recommendations, the Fermilab director has given nuSTORM Stage 1 approval and, contingent upon funding from the DOE Office of Nuclear Physics, has also given Stage 1 approval to the Drell-Yan experiment with a polarized target.

The PAC is composed of senior scientists from universities and high-energy physics laboratories in the United States and abroad. It is a major source of advice to the director about the future direction of Fermilab's experiments and programs. Ever since Fermilab's early days, the PAC's recommendations and comments have offered insight into opportunities and issues important to members of the laboratory community.

"One thing our community is not short of is ideas," said PAC Secretary Steve Geer. "This makes our PAC meetings interesting and promises an exciting future."

From the Scientific Computing Division

Synergia pushes the state of the art

Jim Amundson

Jim Amundson, deputy head of the Computational Physics Department and leader of the Computational Physics for Accelerators Group, wrote this column.

In an era when the field of particle physics is looking to decide what accelerator projects to pursue, accelerator modeling expertise is of tremendous importance. Fermilab's Synergia simulation tool is helping accelerator experts here and at CERN optimize their machines and plan for the future.

A little over 10 years ago, a small accelerator modeling team at Fermilab received its first grant from the then newly established Scientific Discovery through Advanced Computing (SciDAC) program. The thrust of this grant was to combine state-of-the-art space charge calculations with similarly advanced software for single-particle beam dynamics—a capability that did not exist in this field at that point. This work requires the sort of advanced high-performance computing (HPC) platforms championed by the SciDAC program. We named our new program Synergia (Συνεργια)—the Greek word for synergy.

Our first application of Synergia in 2002 was to improve the modeling and, ultimately, performance of the Fermilab Booster, when the delivery of protons for the Tevatron collider experiments and MiniBooNE were the lab's highest priorities. After our initial successes modeling the Booster, we have continued to use SciDAC to enhance Synergia through both funding and collaborating with other physicists and computer scientists. In the past decade Synergia has evolved into a general framework for the calculation of intensity-dependent effects in beam dynamics. And while running Synergia efficiently on 128 parallel processors used to seem like a major accomplishment, we now have demonstrated efficient running on 131,072 cores, keeping us at the leading edge of the rapidly changing field of HPC.

The Synergia project continues today under the third incarnation of the SciDAC program as part of the Community Project for Accelerator Science and Simulation (ComPASS) collaboration, which is led by SCD's Panagiotis Spentzouris. This year, I am the principal investigator of a sought-after INCITE award for computing time on Argonne's state-of-the-art high-performance Blue Gene supercomputers. The award is for 80,000,000 core hours.

At Fermilab, the shift in emphasis to the Intensity Frontier is a natural fit for Synergia, since studying intensity-limiting effects is our bread and butter. We are currently applying Synergia to simulations of the Main Injector for Project X and the Debuncher for Mu2e while continuing studies of the Booster.

Synergia's reputation as an important accelerator modeling framework is growing worldwide. CERN recently announced that it will use Synergia for simulations of space charge as part of the Lattice Injector Upgrades portion of the High-Luminosity LHC upgrades.

We are looking forward to continuing the success of this program by expanding Synergia's capability to efficiently use the best new computing hardware in order to enable more and better accelerator science applications.

Safety Update

ESH&Q weekly report,
July 2

This week's safety report, compiled by the Fermilab ESH&Q section, contains no incidents.

Senate FY 2014 Department of Energy funding bill: Office of Science

From FYI: The AIP Bulletin of Science Policy News, July 2, 2013

The House and Senate Appropriations Committees have completed work on their versions of the FY 2014 Energy and Water Development Appropriations Bill. The House Appropriations Committee approved its version of this legislation on June 26; the Senate Appropriations Committee approved its bill on June 27.